Project Summary/Abstract Depression is a highly prevalent and chronic mental health disorder that significantly contributes to financial and disease burden globally (Ferrari et al., 2013). Measurement-based care (MBC) is an evidence-based practice that may be the minimal intervention needed to improve depression care in community settings (Scott & Lewis, 2014). MBC is defined as the process of basing mental health care practices on routine measurement of client depression symptoms. Simply providing clinicians with client symptom scores improves outcomes and reduces clinical deterioration (Lambert et al., 2003), and studies suggest that enhanced outcomes may be due to increased client treatment engagement (Eisen, Dickey, & Sederer, 2000), improved client symptom understanding (Dowrick et al., 2009), and optimized psychotherapy intervention dosages (Rush, 2015). However, how clinicians use MBC in psychotherapy and the mechanisms by which MBC operates have yet to be empirically evaluated in adult depression treatment. There is a critical need to identify MBC's mechanisms of action to isolate its core components in order to streamline implementation. The proposed study fills an important gap by exploring the mechanism(s) by with MBC acts to enhance depression care. This study serves as the first step in my long-term goal of enhancing depression treatment through the identification and integration of core components of evidence-based practices into community mental health care. This application leverages mixed method data to identify clinician patterns of MBC use in psychotherapy sessions within 12 community mental health treatment clinics in the context of a large R01 randomized implementation trial. The proposed study will explore how clinicians use MBC and how MBC works to improve client outcomes via two specific aims: Aim 1) To characterize the variation in clinician approaches to integrating MBC into clinical sessions across treatment, and Aim 2) To identify the mechanism(s) by which depression symptoms change in concert with MBC fidelity. This study is significant because it: (a) leverages MBC, an intervention with great potential for broad reach and impact as compared to complex, theory-specific psychotherapies; (b) will be the first test of a theory of behavioral responses to feedback in an applied mental health context (Feedback Intervention Theory; Kluger & DeNisi, 1996); and (c) will have important implications for identifying minimal interventions necessary for depression symptom change. The proposed study is innovative because no previous research has identified how MBC is implemented in therapy sessions for adult depression or how it functions to improve depression symptoms.